1. Technical Field of the Invention
This invention relates to amine terminated polyamides. More particularly, this invention relates to amine terminated polyamides having an average molecular weight of about 3,000 to about 10,000 which are useful in the preparation of adhesives, elastomers, polyamide-polyurea foams, polyepoxides, polyimides, etc.
Still more particularly, this invention is related to the preparation of normally liquid amine terminated polyamides having a molecular weight within the range of about 3,000 to about 10,000 and to a method for the preparation of such amine terminated polyamides by the reaction of an aromatic or an aliphatic dicarboxylic acid with a first higher molecular weight polyoxypropylene diamine and with a second lower molecular weight polyoxypropylene diamine.
2. Prior Art
It is known, as exemplified by Yeakey U.S. Pat. No. 3,654,370 to prepare polyoxyalkylene polyamines by the reductive amination of a polyoxyalkylene polyol. The reductive amination is conducted catalytically in the presence of hydrogen and ammonia and an appropriate reductive amination catalyst, such as a nickel, copper and chromia catalyst. The polyoxyalkylene polyamines that are prepared in this fashion are stable articles of commerce having a wide variety of uses such as those mentioned above. In particular, they have found utility as curing agents for epoxy resins, as plasticizers, as cross linking agents and binders for textiles, and as intermediates in the preparation of polyureas. In general, polyoxyalkylene polyamines having molecular weights ranging from about 200 to about 5,000 can be prepared by the Yeakey process.
Klein U.S. Pat. No. 4,133,803 discloses thermoplastic adhesives having a melting point between 20.degree. C. and 180.degree. C. prepared from polyoxypropylene diamines and triamines and mixtures thereof having molecular weights of about 190 to about 3,000 and aliphatic or aromatic dicarboxylic acids, esters and anhydrides thereof containing about 2 to 30 carbon atoms per molecule. The polyoxypropylene amine component and the dicarboxylic acid component are reacted in the mole ratio of about 0.25:1 to about 4.0:1. The thermoplastic adhesives of Klein are useful in the preparation of "hot melt" adhesives. In Example I, a thermoplastic adhesive prepared by reacting a molar excess of a polyoxypropylene diamine having an average molecular weight of about 230 with isophthatic resin at a temperature of 200.degree.-240.degree. C. was formulated at 140.degree. C. with an epoxy resin, a plasticizer and silica to provide adhesives that were applied to substrates with good results.
Yeakey et al. U.S. Pat. Nos. 4,128,525 and 4,182,845 are directed to thermoplastic adhesives of the type disclosed in Klein U.S. Pat. No. 4,133,803 modified by the inclusion of piperazine together with the polyoxypropylene diamine or triame as a reactant, the piperazine constituting at least 80 mole percent of the amine component.
In Kuceski U.S. Pat. No. 4,182,844 an energy-conserving method is disclosed for use in the manufacture of polyaminoamides of the type prepared by reacting a polycarboxylate ester with a mono- or polyalkylene polyamine wherein the reactants are externally heated only to a temperature (e.g. 125.degree. C.) at which the exothermic reaction becomes self-sustaining, after which external heating is discontinued. The desired temperature range is thereafter maintained because the heat of reaction is used to vaporize by-product water and alcohol from the reaction mixture.
Impact resistant thermoplastic polyamides useful in the preparation of holt melt adhesive formulations by interreacting 57.5-94.75 mole percent of a short chain polyamide forming moiety such as a dicarboxylic acid or a diamine with 5-30 mole percent of a polyamide-forming dimer acid moiety and 0.25-12.5 mole percent of a polyamide-forming moiety such as an amine or carboxy terminated butadiene-acrylonitrile copolymers or poly(oxyalkylene) diamines.
Bentley et al. U.S. Pat. No. 4,751,255 relates to polymeric polyamines having molecular weights ranging from 1,000 to 16,000 and containing from 2 to 4 primary amino groups per molecule which are prepared by reacting a polycarboxylic acid or ester with a stoichiometric excess of a polyamine having terminal aminopropoxy groups and a molecular weight of less than 500. In an example, a molecular excess of a polyoxypropylene diamine having an average molecular weight of about 400 was reacted with dimethyl terephthalate to provide a product having a viscosity of 931 centistokes at 100.degree. C.